The invention relates to a mist generating head. Such known mist generating heads are employed, for example, in appliances used to increase the moisture content of ambient air or also in industrial installations, in which, for example, a film of oil or a coating of adjacent oil droplets is applied to the surface of a workpiece.
What the known mist generators have in common is that it is difficult to produce mist also from liquids of higher viscosity for, in said case, the gas jet meeting the liquid stream delivered by the liquid nozzle may no longer subdivide the liquid stream into individual droplets because the cohesion in the liquid stream is too great. Also, with the known mist generators, the generated mist quantity may not be adjusted to very low values because atomization of the liquid by means of a gas jet presupposes a specific minium flow rate of liquid through the liquid nozzle and of gas through the gas nozzle.
The object of the present invention is therefore to develop a mist generating head in a way that allows also small quantities of a liquid of higher viscosity to be reliably atomized.
According to the invention said object is achieved by a mist generating head having the features disclosed in the present invention.
In the mist generating head according to the invention, there is forced subdivision of the fed liquid into small packages by the valve body associated with the liquid nozzle. Said small liquid volumes, which are delivered each time the valve body opens, are then split up further by the gas flow so that, on the whole, a fine mist is obtained.
Good preliminary dispersion of the liquid at the liquid nozzle is obtained when the valve body cooperating with the liquid nozzle is operated at the frequency disclosed in the present invention
The pressure value indicated in the present invention for the liquid to be atomized and the pressure value indicated in the present invention for the gas are advantageous likewise in view of fine, reliable nebulization of the liquid.
The geometry of the mist generating head as disclosed in the present invention has the advantage that, on the one hand, the liquid droplets derived by the liquid nozzle reach and pass through the gas jet and, on the other hand, a specific concentration and spatial confinement of the mist is effected by the gas jet and, moreover, the mist generation as a whole is effected symmetrically and uniformly.
The effect achieved by disposing the valve body axially outside of the liquid nozzle as disclosed by the present invention is that the valve body acts simultaneously as a deflector, by means of which the liquid droplets delivered by the liquid nozzle are distributed in peripheral direction.
In a mist generating head of the present invention, the gas nozzle, viewed in flow direction, may be disposed downstream of the liquid nozzle such that the stream of droplets delivered by the liquid nozzle may widen slightly before the fine atomization by the gas flow is effected. The result is better surfaces for the gas flow to act upon.
According to the present invention, the gas nozzle at the inlet side has a recess that serves to collect the mixture of droplets and gas before running into the gas nozzle, which has only a small diameter.
When an injection nozzle unit of the type indicated in the present invention is used to realize the liquid nozzle and the valve body, the cost benefits, stability under load and reliability of injection nozzles for i.c. engines may be turned to good use for nebulization of a liquid.
The development of the invention is advantageous both in view of a compact design of the mist generating head and in view of the uniformity of the generated mist.
With the development of the invention, a shaping and/or confinement of the mist stream generated by the mist generating head is obtained.
According to the present invention, the cross-sectional shape of the mist stream may easily be increased or decreased in size.
This may be realized according to the present invention by means which are mechanically extremely simple.
The effect achieved by the development of the invention is that the cross section of the mist stream may be adjusted to suit prevailing requirements by means of a control device.